1// Copyright 2021 Google Inc. All rights reserved.
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7// http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15#include "perf_counters.h"
16
17#include <cstring>
18#include <vector>
19
20#if defined HAVE_LIBPFM
21#include "perfmon/pfmlib.h"
22#include "perfmon/pfmlib_perf_event.h"
23#endif
24
25namespace benchmark {
26namespace internal {
27
28constexpr size_t PerfCounterValues::kMaxCounters;
29
30#if defined HAVE_LIBPFM
31const bool PerfCounters::kSupported = true;
32
33bool PerfCounters::Initialize() { return pfm_initialize() == PFM_SUCCESS; }
34
35PerfCounters PerfCounters::Create(
36 const std::vector<std::string>& counter_names) {
37 if (counter_names.empty()) {
38 return NoCounters();
39 }
40 if (counter_names.size() > PerfCounterValues::kMaxCounters) {
41 GetErrorLogInstance()
42 << counter_names.size()
43 << " counters were requested. The minimum is 1, the maximum is "
44 << PerfCounterValues::kMaxCounters << "\n";
45 return NoCounters();
46 }
47 std::vector<int> counter_ids(counter_names.size());
48
49 const int mode = PFM_PLM3; // user mode only
50 for (size_t i = 0; i < counter_names.size(); ++i) {
51 const bool is_first = i == 0;
52 struct perf_event_attr attr{};
53 attr.size = sizeof(attr);
54 const int group_id = !is_first ? counter_ids[0] : -1;
55 const auto& name = counter_names[i];
56 if (name.empty()) {
57 GetErrorLogInstance() << "A counter name was the empty string\n";
58 return NoCounters();
59 }
60 pfm_perf_encode_arg_t arg{};
61 arg.attr = &attr;
62
63 const int pfm_get =
64 pfm_get_os_event_encoding(name.c_str(), mode, PFM_OS_PERF_EVENT, &arg);
65 if (pfm_get != PFM_SUCCESS) {
66 GetErrorLogInstance() << "Unknown counter name: " << name << "\n";
67 return NoCounters();
68 }
69 attr.disabled = is_first;
70 attr.pinned = is_first;
71 attr.exclude_kernel = true;
72 attr.exclude_user = false;
73 attr.exclude_hv = true;
74 // Read all counters in one read.
75 attr.read_format = PERF_FORMAT_GROUP;
76
77 int id = -1;
78 static constexpr size_t kNrOfSyscallRetries = 5;
79 // Retry syscall as it was interrupted often (b/64774091).
80 for (size_t num_retries = 0; num_retries < kNrOfSyscallRetries;
81 ++num_retries) {
82 id = perf_event_open(&attr, 0, -1, group_id, 0);
83 if (id >= 0 || errno != EINTR) {
84 break;
85 }
86 }
87 if (id < 0) {
88 GetErrorLogInstance()
89 << "Failed to get a file descriptor for " << name << "\n";
90 return NoCounters();
91 }
92
93 counter_ids[i] = id;
94 }
95 if (ioctl(counter_ids[0], PERF_EVENT_IOC_ENABLE) != 0) {
96 GetErrorLogInstance() << "Failed to start counters\n";
97 return NoCounters();
98 }
99
100 return PerfCounters(counter_names, std::move(counter_ids));
101}
102
103PerfCounters::~PerfCounters() {
104 if (counter_ids_.empty()) {
105 return;
106 }
107 ioctl(counter_ids_[0], PERF_EVENT_IOC_DISABLE);
108 for (int fd : counter_ids_) {
109 close(fd);
110 }
111}
112#else // defined HAVE_LIBPFM
113const bool PerfCounters::kSupported = false;
114
115bool PerfCounters::Initialize() { return false; }
116
117PerfCounters PerfCounters::Create(
118 const std::vector<std::string>& counter_names) {
119 if (!counter_names.empty()) {
120 GetErrorLogInstance() << "Performance counters not supported.";
121 }
122 return NoCounters();
123}
124
125PerfCounters::~PerfCounters() = default;
126#endif // defined HAVE_LIBPFM
127} // namespace internal
128} // namespace benchmark
129